Engineered plastic solutions

Tag Archives: plastics for machining

A plastic part by any other name would still be a plastic part, wouldn’t it? Yes it would. But the way those plastic parts produced; either by molding plastic parts or by machining plastic parts are dramatically different. Those differences in the process of making plastic parts can result in big differences in lead times, cost, and quality. Below are things to consider when looking at how to manufacture plastic parts and some answers that may help you to decide.

How Many Plastic Parts do you Need to Make?

MOLDED: Molded Plastic parts have been around since the first machine for the process was patented in 1872 by John Wesley Hyatt and his brother Isaiah so its easy to see how this became one of the standard processes for creating plastic parts. Mold machines are used to run mass produced plastic parts from tooth brushes to auto parts and everything in-between. Creation of the mold(s) costs thousands of dollars, requires time up front to make the mold(s) and the molds require maintenance over their life and storage when not in use.

MACHINED: Depending on the project, volumes from 25 to 5,000 parts can often be machined more cost effectively than molded. For small parts, you may have a lower final cost by using high performance screw machines that can run circles around expensive multi-cavity molds. This means shorter lead times than molded parts and little up front cost. Machined parts don’t require secondary machining to clean a part once it is ejected from the mold.

Will You Need to Make Changes to Your Part Design?

MOLDED: Parts made from molds require that the mold be made first which is more time and expense up front. In addition a mold will require maintenance over it’s service life and storage space when it isn’t in use. Changes to a mold are costly in terms of time and dollars to either change or make a new mold, depending on the changes needed.

MACHINED: Machined parts allow for shorter lead times and flexibility in making design changes because they are run directly from a CAD file. Overall, machining can be used to create very complex parts including parts with undercuts and thick walls and the materials are more homogenous across the length and width of the part.

How Important Are Tight Tolerances and Dimensional Stability?

MOLDED: Every plastic behaves differently. But in general plastic parts made from molds may not be as dimensionally stable as machined parts. There is more chance the parts will not be as homogeneous across the length and width of a part. The molding process is not ideal for large parts or where there are thick walls. Tolerances of +/- .005″ are typically the best that can be achieved in molded parts. This compares to +/- .001″ for machined parts.

MACHINED: Many of today’s high performance engineering plastics, such as DuPont Vespel, PEEK, PBI or others can take extreme temperatures of 250 or even 450 degrees and remain dimensionally stable. Many of these materials are also chemical resistant. Additionally machined parts have less internal stress and tolerances of +/- .001″ or better can be achieved.

How Large or Complex Are Your Parts?

MOLDED: Small to mid-size plastic parts can work well. Large volumes can be run fast. But large plastic parts with thick walls, or complicated undercuts can be an issue for mold design. Materials cooling at different temperatures within a mold can result in more internal stress and a less homogeneous material. Undercuts can pose a mold design challenge with how to release the part from the mold. Plastic parts fresh from the mold may require secondary machining to remove flash, parting lines, or ejector marks, adding to production time and cost.

MACHINED: Large parts and parts with complicated undercuts can be made quickly and efficiently by machining processes. Thick cross sections will have higher, more consistent mechanical properties. Again, because there is no mold to be made, the up front investment and lead time is much shorter. Machining also handles threading extremely well and machined parts will have no parting line, ejector marks, or flash. The availability and selection of engineering plastics means many prototypes can be made in production-equivalent materials. Plastics are more often being found to be a good alternative to metals. They can often be machined on the same equipment and many high temperature engineering plastics offer features such as lightweight, flexibility, high strength, resistance to corrosion, excellent durability, high heat tolerance and chemical resistance. Some plastics, such as those for bearings even require little or no lubrication making them even more cost effective on the service end.

The moral of this blog – a plastic part by any other name is still a plastic part but how you get to create that part could make all the difference in the world. Molded plastic parts have their place, but before going down the path of investing in molds it may be worth a little time considering the questions in this blog and determining if molded or machined is the best option.

After a year or more of research and hard work to expand, AIN Plastics is pleased to announce the opening of a new AIN Plastics Distributor Branch in the St. Louis Missouri area.

New Business Locations Don’t Happen Overnight

This week I had the opportunity to talk with Chris Urban, Branch Manager for AIN Plastics new St. Louis Area Distribution Facility. I asked him what it took to get a new branch opened up. Chris said they started with finding the right location, which turned out to be in the same building as the St. Louis area ThyssenKrupp Materials NA Facility (AIN Plastics parent company since 1993). Then came finding the right equipment which includes a brand new saw for custom cutting orders and finding just the right people with both customer service and previous plastics experience. Chris noted they wanted to hit the ground running from their first day of business. He went on to say:

“We have worked hard in preparation over the past year prior to our opening and we are very excited to see our hard work pay off. ThyssenKrupp Materials NA, AIN Plastics Division did a great deal of research regarding this project. St. Louis is an ideal location to further extend our distribution. From this branch we will be able to provide customer service and quick turn around on orders to Missouri and surrounding states.”

Chris also said he wanted to thank all the AIN people that came to St. Louis from other branches to support his team for the first few days. “Having the support of the entire AIN Plastics company has made starting the new branch a great experience for everyone. We feel truly supported and connected to everyone in the company.”

AIN Offers More than Materials – It’s about Value Added Services

I asked Chris about the services they will be offering. Chris says the new AIN Plastics distribution branch offers a comprehensive list of value added services including:

Close tolerance custom cutting of orders

Customized Inventory and stocking programs including just in time delivery solutions

A vast inventory of sheet and rod materials, some of them highly specialized

Professional team with years of plastics industry experience

ThyssenKrupp Nationwide Logistics for the best possible delivery

More Manufacturers are Choosing Plastic Due to it’s Many Benefits

Chris talked about how the selection of plastics is changing rapidly due to its value as a lightweight component in manufacturing, it’s ability to be reused and recycled, and it’s cost. Plastics are often an affordable material compared to more traditional resources such as metal, wood, or glass, and they often outlast and outperform those materials. Researchers are always developing even better plastics. “We have a team in place that can help customers sort through and not just find a plastic that will work, but rather the right plastic for their application.”

Plastics, Plastics, and More!

When it comes to what plastics the St. Louis AIN Plastics branch will stock, Chris gave me a short rundown and said this doesn’t come close to covering all the materials we have:

Industrial Plastics

High Pressure Laminates

Engineering Plastics including

ABS

Acetal

Cast Acrylic

Polycarbonate

Radel R

Semitron

Techtron

Composite Tooling products

RAMPF Styling, Modeling, and Tooling Boards

RAMPF Close Contour Paste and Casting Materials

Thermoform Materials

Epoxy Casting and Laminating Resins

Foundry and Pattern Materials

Plastic Tubing including Medical and Food Grade

FDA compliant plastics for medical and food service industries

Silicone

Rapid Prototyping

DuPont TM Vespel® (AIN Plastics is the Authorized Distributor)

Well, you get the idea, it’s a long list and that’s just the beginning. Chris says the best way to learn more is by visiting the website ainplastics.com or better yet by giving them a call at 877.246.7700.
The AIN Plastics Distribution Facility is located next to the ThyssenKrupp Materials NA facility:

59 Interstate Drive
Wentzville, MO 63385

Hours of operation are Monday – Friday 8:00 AM – 5:00 PM.

For more information regarding the new AIN Plastics St. Louis Area Branch

That’s it for this week’s news. Look for our other posts where we look not at ourselves, but at the world of plastics. What’s new, what works, why certain plastics are good in specific applications and more. IF you do want to learn more about AIN Plastics and our history check out the “About Us” page on our site.